Transmitting apparatus for remote control systems



A. P. JACKE L 2,393,371

TRANSMITTING APPARATUS FOR REMOTE CONTROL SYSTEMS Jan. 22 1946.

Original Filed Jilly 31, 1945 Y L FH W g Lgflllll l W U .P w Pp W Z H13 ATTORNEY Patented Jan. 22, 1946 mmsmrqrmcnrmnhws "no-ii nnMoirE i SYSTEMS Arthur P. Jackel, 'Wi'lkinsbur g, 4a., assignor to I 1 The Union .Switch 8; Signal Company, Swiss-. vale, Pa, acorporation of Pennsylvania I Orig-ina'l application July '31, 1943; SeriillNoL 496,907. Divided and this application tSeptema 1 ber15,1944,":Serial No. 5549200 v '8 claims; 7 .01. 177- 380) My invention relates to transmitting apparatus e for remote control systems, and more particularly for centralized tra flic con'trol systems ior railroads comprising an :office and a plurality of-stations connected by line wires over which impulse code signals are transmitted to cheat theoperation-of trafiic governing devices located along the trackway, and to indicate the condition of such 1 devices at the office.

This application is 'adivision of co-p'ending .application,Serial No. 496,907, filed -July 31', 1943, for Remote control systems. g

The :system of my invention is of the time code type, employing codes of long :and short elements which are 'transmitted one at a time over a single line circuit, and-is :based upon the system shown in Letters Patentof the United States No. 2,229,249 granted "January '21, 194 1, to L V. Lewis, for Remote control-systems. Mysystem includes also certain -improvements upon thesysitem of this patent relating'to mouse or a ceniibattery line circuit of the bridged type first shown inLetters Patent of the Unied States No. 2,3fl3;875l, granted. December .1942, to G. W.

Baughman and vNF. Agnew, for Remoteconttol systems; I r o .zlthe coinponents of the system of my invention .are zprefserablyassembled in the form of coding -an1'd storage units each containing group of .:relays EEhe system employs a station, coding uni-t at'each field :location for transmittingiindication codes for selectively :receivmg control codes, together with :a station storage'unit ifor'each unit :group of. controlled trafiic governing devices, for associatingsuch devices with the-station coding unit. The office equipment. preferably includes an individual control panel for each unit vgroup ofrcontrolled traflic governing. devices, and an office coding unit which is connected over the line "circuit with the vstation coding units to establish communicationzselectively between each panel and the corresponding station storage :unit. The invention of the present application-relates to improvements in the station coding and" storage units and to :the transmittingapparatus associated therewith, employed for the transmission proverltneans for the itransmissi'onsof indications of rtrain movements, comprising an improved track 'Os storage arrangement for insuring the rtran ismission oi an indication "Ofj'fi, trainmove ment. through in. particular. track section, even though the line :circuit .is not Yaivailable when the traintvmovement'takes mlace.

The system "of my invention also includes circuit improvements whereby the timingof there- -1ES1Whi0h measure the .-1engths--of thercode'elelunentsis more "accurately controlled, as 'will here matter be pointed out, "thereby increasing the margin of reliability oft-he system, and causing .it vto function properly through" 1a wideri=ra1 e of "variation of local 'battery voltage. I

V a In the accompanying drawing I have-illus- .of indication codes from the several stations. to

tl1econtrol oflice. 9116 feature of my invention comprise the provision :ofta starting rlelaybf the normally ener- 'g'ized type :in each station storage unit, which is v ofl-myinventionzrelates twinit-rated in condensed form the iield station equipmentemployed in one form-of centralized traflic control system embodying invention, torgen- -erating .ariddelivering indication codes to the :line CiICHZi-f QOHlPI'iSilflQ" the transmitting porton oi the station-coding unit together withfa portion of one storage unit, arranged as required when there isbut one u nit group of movable devices at the. location, to be indicated at the office.

Referring to the drawing, 5 he reference charroactersx-Y; -,and-Z designate fa. pair of line wires whichextend from the office through thekseveral stations and provide a line circuit ior the-centralized tra-fiic control system of my inven-tion. .This line circuit, :aS-ShQWn', is nonnallyie'nergized by current irom'th e or fice line battery '80, the positive terminal of is-norcmally connected to -line wire Yeand the negative terminalto line wire Z over b-ac'k contacts 1) and d 'of' a .pole changer relay-PC and of an oifice transmitter relay {and the ofLaJow pass .filter The circuihalso includes the primary windings .of an i-mpulse transformer RT, yrmeans of which the ofiice (line relay ORis controlled when receiv- :ing indication code s, RelaycQRIisfof 'the .s'tick polar type, as described and claimed Patent .No. 2,303,875, and responds to impulses of alternately opposite polarity deliveredby transformer when the line. current is varied -by the-opera- @tion :of a station transmitter'relay T. Indication codes ;are. transmitted by energizing the, master r ay a at o in e ay e eat l to connect the -l-ine- -wirestogether periodically minal C of the source.

through an impedance of relatively low value in comparison with the normal impedance of the line circuit, comprising the coils of a low pass filter LPF similar to the one at the ofiice, which is interposed between the line and the station apparatus.

At each'field station, as shown, a high resistance line relay R is connected across the line wires Y and Z in series with a resistor WI, the connection normally including back contacts I) and d of the master relay M and the coils of the low pass filter LPF. The station line relays R are of the biased polar type andare normally energized, in parallel, by current supplied by battery 80, each relay R closing its left-hand contacts a and b, as shown, when its left-hand terminal is positive, and closing its right-hand con-f tacts a and b when energized in the reverse direction with its right-hand terminal positive, or when deenergized.

Each station line relay R controls a group of slow' release timing relays LI, L2, LP, LB and LBP. These timing relays are normally deenergized and are controlled by relay R to govern the transmission of codes in accordance with' line conditions like the similarly designated relays of Patent No. 2,229,249, hereinbefore referred to. Their release times are likewise governed by electronic rectifiers, as shown, the rectifiers' also serving to prevent contact sparking and to minimize contact wear, as explained in this patent. Certain of the relays shown herein, such as the relays FA, GA and I6, are provided with a discharge circuit including a resistor in lieu of the usual rectifier. These resistors are of relatively high value in comparison with the resistance of the relay winding and provide less retardation, but otherwise serve the same purpose as a rectifier.

The system of my invention is arranged to employ indication codes each having sixteen steps, and in each indication code delivered by a station transmitter relay T, the front contact b of relay T closes to shunt the line circuit at the beginning of each odd-numbered step, short circuiting the associated line relay R to cause it to release, and increasing the current delivered to the line by battery 80, so that relay OR assumes its reverse position. Front contact b of relay T is opened at. the beginning of each even-numbered step and relays OR and R then assume their normal positions as shown. Each step is made relatively short or long to provide code character, both the open and closed periods constituting code elements.

When the line relay R releases at the begin ning of a code, its right-hand contact 1) completes a circuit from the positive or supply terminal B of a suitable local source of current over a back contact d of relay I6, back contact a of relay L2, back contact g of relay LBP through relay LI to the negative or commonreturn ter- Relay LI then picks up and its front contact a completes a circuit from terminal B at the right-hand contact I) of relay R through relay L2 to terminal C, so that relay L2 picks up, completing a stick circuit at its own front contact a and also completing a circuit from terminal B over front contacts of relays LI and L2 to pick up relay LP, which relay in turn completes circuits over its front contact a to pick up relays LB and LBP. Relay LBP becomes energized in tandem with relay LB when the latter closes its front contact a so that these relays release successively after relay LP is released. When relay L2 picks up on the first step of a code, its contacts a and g shift the connections of relay LI from the right-hand to the left-hand contact b of relay R, and then contact 9 of relay LBP is picked up to maintain the latter connection until the code is terminated. It follows that relays LI and L2 are energized alternately, relay LI over the left-hand contact I) of relay R, and relay L2 over the right-hand contact 17 of 'relay R, in response to the periodic operation of relay R. Relays LI and L2 remain pickedup for the duration of short code elements, relay LI releasing during each odd-numbered long element and relay L2 during each even-numbered long element. These relays serve, therefore, to indicate code character in a code to which relay R responds, and together with relay OLBP, which function in a similar manner. Re-

lay OR, however, is normally deenergized and is adapted to hold its contacts in either position to which it is operated by a momentary impulse,

and hence it may become accidentally reversed.

If this occurs, relay OR is restored automatically to normal by the action of the timing relays in a manner explained in my prior application, Serial No. 496,907, and it may be assumed therefore that relay OR, although deenergized, occupies its normal position corresponding to that of the normally energized station line relays R, when the system is in its normal at rest condition.

Each line relay R controls a chain of counting relays I to 8 and I6, over circuits generally similar to those of Patent No. 2,229,249. In response to the first of a series of operations of relay R, a pick up circuit for relay I is closed momentarily from terminal B at the right-hand contact a of relay R over back contact e of relay I6, back contact b of relay LBP, front contact g of relay LI, through relay I to terminal C. Relay I therefore picks up on the first step of a code upon the energization of relay LI, and when relay LBP picks up, it opens the circuit just traced and closes a stick circuitfor relay I extending over front contact b of relay LBP, wire II9, back contact b of relay 2, front contact a and winding of relay I to terminal C. Whenr'elay R is operated to normal to begin the second step of a code, terminal B is disconnected from relay I, which remains picked up due to the discharge path provided by the rectifier connected to wire H9, and a circuit is closed from the left-hand contact a of relay Rover front contact d of relay LBP, wire I20, back contact a of relay 8, front contact b of relay I through relay 2 to terminal 0. Relay 2 therefore picks up and completes its stick circuit extending to terminal B at wire I20 over its front contact a and back contact b of relay 3. The operation of contact b of relay 2 disconnects relay I from the rectifier. but closes a second discharge path for relay I comprisin the winding of relay 3, whereby relay .I releases shortly after relay 2 picks up but without sparking at its contact a, the dropping of which connects relay 3 to wire II9 to condition that relay to respond to the third 'step 'of the code; Relays 4 to 8 are similarly controlled u one at a time by current steps are properly carried out, a, chain repeat relay CE is; picked up on the'eighth step, as hereinafter described, to prepare a pick-up circuit for relay I over front contact. b of. relay 8 so that relay 1- will operate as the next in order after relay 8-, relays l to 1 being then operated through a. second cycle on the ninth to fifteenthstepsofthe code, relay l6 responding in place. of relay 8 on the sixteenth step, during which the apparatus i'srestoredto its normal at rest condition.

As expl'ained'in my prior application, Serial No. 96 ,907, the line wires Y and'Z arevused for two-way transmission, that is; to transmitindication codes from'the stations to the office, at times, and at other times to transmit control codes from the office to the stations, and to make the station coding units function as selective receivers of the codes which'originate atthe oifice, the first step of each control code is made a long step to distinguishit from an indication code in. which the first step is relatively short.-

On' the first step of a control code, a deliver control relay CD is selectively operated at'each station, in response to the release of relay Ll, due to the long character of the step, over'a circuit extending from terminal B at 'frontcontact a of relay LBP, 'wire' I60, back contact d of relay Lt, back contact b of relay CR, front contact c of relay I, through the upper winding of relay CD toterminal C. When 'relay CD picks up, it completes a stick circuit from terminallB atwir'e 1 50 over its contact a and lower windin to terminal C. v a 1 Relay CD does not pick up on the first step of an indication code transmitted by the associated station transmitter, unless it happens that a-control code is initiated by the 'ofiice transmitter OT at the same time. When this'occurarelay CD servesas. a lock out relay to prevent further transmission of the indication code until the [control code is completed, as hereinafter explained. I I i The second to eighth steps of each code maybe arranged in any one of thirty-five dilierent combinations of. three; long and four-short steps to form station code calls, which are identified by istered at the transmitting stationby the energization of a set of three selector relaysl A, GA and S, whichmay' be adjustably connected to contacts at of the counting relays so as to respond.

to anyone of the thirty-five code calls, the'co-n nections being. arranged so that relay S is respon-f sive to' the code; call delivered by the associated transmitter; The circuits for the selectorfrelays. which respond on even-numbered steps extend from terminal .B at front contact a of relay LBP, over wire 168', back contact d of relay L2, back contact 12 ofrel'ay CR, back contact e of relay and thence. over front contacts d; of relays and 8 to wires "I22, 121-,

9 I26 and-t2 8 a connection to wire I 22 provides a circuit for energizing relay FA on the second step, relay FA having; a stick circuit: extending to: wire Millover its own front contact a, and a back contact m: of relay GA. The circuits for the selector relays which respond on odd-numbered steps extend from terminal B at wire [6o over back contact of relay -L| back contact b of relay CR, back contact d of relay LP, and thence over front contacts d of relays 3, Eand I to Wires I 23, [25 and IN. As shown, a connection to wire [23 provides a circu-i-t overcontact b: of relay FA for energizing relay GA, the stick circuit for which extends: to terminal B at' wire tiit over its own frontcontacta and back contact a' ofrelayS; Similarly, a. con-'- nection to-wire: 24 provides a circuit over contact b-of relay GAfor energizingrelay S, the stick. circuit for which is connected directly to term-i nal B at wire 1-69: over its. own. front'contact a;

It is tobe noted that the selector-relays FA, GA and S are operated in response to the release. of.

relay LP',-following the release of relay LLor These relays control relay wTby opening the connections to. the wires l'32 |.=38; and thereby" serve to terminate the long steps of the station code call.v I

It isto be understood that the relays FA. at the different stations may be: connected to. any of the wires I22 to. ['25, and the relays GA to any of. the wires lit-to: I:2.l'.at the right of the one to which relay-FA is connected, while relay S may be connectedto any of thewires I2 4 to. l 2.3 at; the right of the onetoiwhich relay GA is. connected.

The energization of relay S prepares a pick-up circuitfor relay CR completedonthe eighth step.

' This circuit. extends fromtermi-nalB at. contact d of relay S, wire M6,. contact f of relay 8,; relay CR to. terminal C, andwhen relay CR. picks up, its: front contact a completes its stick circuit extend ingto: terminal 3 over wire 1.5.9. Front contact of relay CR completes a connection fromwire. I Hi over1back contact a of relay I to contact 22 of relay 8 for effecting the operation of relay, l on the ninth step, and front contact h of relay CB completes a connection over back contact o of. relay 8 for energizingv relay iii in place of relay 8, on the sixteenth step. 'Iheninth to fifteenth stepsrof: the code may be made long or short to indicate the condition of seven movable devices at the station. ,To simplify the drawing. only three such devices are shown,,:these comprising therepeating'. relay TK-S controlled by the indicating. relay and the indicating relays NWP and RWP; The. station apparatus is arranged to initiate aniin-dicationcode automatically in response to a change in position of any of these indicating relays, eachsuch code being stored for transmis-- siorr when the line: circuit becomes available, by theirelease of the station starting relay ST. Relay S'Iis normally held energized over-a stick circuitv extending from terminal- B at its ownfront con tact a, overback contact e of relay S, the winding ofrelaySTand thence over a front orback contact c ofreach of the'severalindicating relays-, i-n series,: to,;terminal C, 'H-eretofore a normally energized starting circuit of this type has been objectedto because of thenecessity for a special'adjustment: of the contacts of the indicating relays in'order tojnsure the releaseof thestartin relay 7 during the: brief periodthe circuit is opened during the. transit of the contactfro-m oneposition toanother; difficulty has been overcome inthe circuits" as shown by the use of a'sensitiverelay of the biasedi polar type having an.-induct-- ance' 10 connected across: its termnialsr. The en ergy stored in coil when relay ST is energized provides a source of induced current for operating relay ST to its reverse position to open its stick circuit in response to any sudden increase in circuit resistance due to the movement of one of the indicating relay contacts 0, even though th time such contact is actually open is substantially zero, consequently no special adjustment of these contacts is needed.

I shall now describe the transmission of an indication code by the station coding unit, assuming the code to be initiated as the result of the release of the indicating relay TR. The opening of contact a of relay TR opens the normally closed stick circuit for relay TKS extending to terminal B at its front contact b, and also opens its pick-up circuit extending from terminal B at back contact 11. of relay MSP, left-hand contact d of relay ST and front contact a of relay TR through relay TKS to terminal 0, and relay TKS releases, its contact 0 in turn opening the stick circuit for relay ST causing it to release.

If the line circuit is available, the starting circuit is closed, extending from terminal B over back contacts b of relays ST and SS, wire I41, contact a of a cut-out relay COR, back contacts b of relays L2 and L1 through relay M to terminal C. Relay M picks up, completing a temporary stick circuit over its contact a extending to terminal B at wire I41 over back contact 0 of relay LBP. Contacts b and d of relay Mreverse the connections of relay R to line wires Y and Z, front contact 01 of relay M also closing a low impedance shunt path from line Y over back contacts f of relays CD and LPB to line Z.

When the line circuit is shunted by relay M, the associated line relay R releases and the increase in current delivered by battery 80 causes transformer RT at the oflice to deliver an impulse operating relay OR to reverse substantially in unison with relay R.

Relay R operates the associated timing relays and relay 9, the closing of contact 0 of relay LB completing the normal stick circuit for relay M extending over wire H8 and back contacts e of relays l6 and CD to terminal B.

Relay OR operates timing relays similar to those shown, including a relay OLBP, and in addition, a circuit is completed from terminal B at the right-hand contact a of relay OR over back contact h of relay OLBP and back contact (2 of a relay 0! 6 through relay PC to terminal C. Relay PC therefore picks up and its contacts b and d reverse the polarity of the current delivered to the line. The variations in the line current due to the operation of relay PC, are devoid of effect upon relay OR, due to the operation of local holding circuits for that relay as described in my prior application, Serial No. 496,907. When relay PC picks up, it is held energized over a stick circuit including its front contact a and front contact h of relay OLBP until relay OIB picks up, relay Ol6 being operated in unison with the station relay' l6 upon the return of relay OR to normal at the end' of the code.

The shunt across line wires Y and Z applied by relay M at the transmitting station as described will also short circuit and consequently release the line relays R at stations more remote from the office. If the transmitting station is at a considerable distance from the olfice it may be that the voltage across the line, which varies from nearly the full voltage of battery 80 at the office to substantially zero at the point where the .shunt is applied, will remain sufiicient to keep the relays R picked-up at stations near the office. These relays, however, will be released by the reversal of line polarity by relay PC. It follows that all line relays R release substantially inunisonwhen any relay M picks up to initiate a code, each relay R operating its timing relays L and. first counting relay I.

At each station at which relay M is not operated, relay R remains released, holding relay L2 energized but allowing Ll to release to pick up relay CD, and then relays LP, LB, LBP, l and CD, release in that order.

At the transmitting station, the closing of front contact e of relay M completes the pulsing circuit for relay'T, which extends from terminal B at back contact'e of relay CD, over back contact e of relay I6 and back contacts g of relays l, 5, 3 and I, contact e of relay M through relay T and resistors W6 and W! to terminal C. Relay T transmits the code by the operation of its contactb which is rendered effective when relay LBP picks up on the first step to open its back contact 1 in parallel therewith. Each time relay T picks up, a low resistance shunt path is closed from line Y over back contact 1 of relay CD, front contact b of relay T and front contact d of relay M to line Z, and at the same time, the circuit for relay R which now extends from the positive wire Z over front contact at of relay M, back contact b of relay T, resistor WI, relay R, front contact b of relay M to wire Y, is opened by relay '1', thereby releasing relay R more quickly than if it was merely short circuited by the closing of front contact b of relay T.

Although the first step of an indication code is short in comparison with the first step of a control code, it is slightly longer than the other short steps, since it begins before relay T picks up, and because relay T is held energized until relay LB picks up, which occurs shortly after relay l picks up to open the pulsing circuit due to the provision of a connection from terminal B at back contact e of relay LBP over back contact d of relay LB to contact e of relay M, and thence through relay T to terminal C. H

The response of the apparatus at the transmitting station as required to allow the transmission to continue is also dependent upon conditions at the oflice. Since the connections of relay R to the line have been reversed by relay M, relay R picks up in response to the release, of relay T to begin the second step only if relay PC has been picked up to reverse the polarity of the line current, this indicating that the ofiice apparatus is in the proper receiving condition.

When relay R picks up to begin the second step, the operation of its contact b re-energizes relay LI and de-energizes relay L2, and the operation of contact a of relay R causes relay 2 to pick up and relay l to release.

The closing of back contact g of relay I completes the pulsing circuit for relay T over contact e of relay M, this circuit functioning repeatedly to generate the short steps of the code. The pick-up time of relay T depends upon the time constant of the circuit including its winding and resistors W5 and W1. When relay T picks up, its front contact 0 short circuits resistor W6 so that the energization of relay T rises quickly to a higher value than would otherwise be the case, and consequently providing a more constant release period under conditions of variable voltage.

Its release period,' it will be, noted, is determined by the time constant of the the code. The code call being 234,.in the case circuit including its winding and resistor WI only,

and it follows that its pick-upand release periods may be adjustedindependently. The circuits for relay T which include contacts e and J of relay 'CR provide connections 7.

:so as to hold :relay '1 picked up af-ter its pulsing circuit opens, to generate the long odd-numbered steps. The remaining connections include contact 7" ofrelay M and backcontact c of relay and provide connections from terminal 3 controlled by the selector relays on steps 28 and by relays Ll and-LP on steps;9--l5 tothe left-hand terminal of relay T which are effective to short circuit its winding and therebyserve as holddown circuits to hold relay'l released after its pulsing circuit closes, to generate the long evennumberedsteps of the code. v I

, in the code being described, it isassumed that the code call is 234, and the second step :is pro- .longed by the closing of a hold-down circuit :for

relay T extending from terminal ".BLOVBI back contacts :0. of relays ST, SS and '53; back contact at of relay GA; back contact e of relayFA-to wire 1 32, thence .over contact .0 of relay} and back contact ,1 of relay CR, contact 7 of relay M, and

back contact .0 ofrelay T to its left-hand terminal; thereby short circuiting relay T. On the second step, relay FApicksup in response to; the

closing of back contact 6 of relay LP over the circuit already traced which includes back contact;

d of relay L2 and wire 122, and the Operation of contact -e of relayFA transfers theconnection of terminal B from wire I32 to wire=l33 opening the hold-down circuit for relay '1 to allow it to pick up to begin the third step. The, third step isprolonged by the operation of the stick circuit for relay T extending from terminal "B over front contact e of relay FA to wire 133,

relay GA transfers the connection of terminalB.

from wire 133 to wire l34, opening'the stick circuit for relay T to allow it to releasetobegin the fourth step, which like the second. is prolonged by the operation of a hold-down'circuit for relay T, the circuit-for generating the long fourth step including front contact 9 of :relay GA, wireJ34 and contact c of relay 4. Relay GA, by opening its contact m, releases, relay FA, and

on the fourth step, the station selector relay S picks up. in response to the closing of back contact d of .relay LP over the circuit which includes back contact at of relay L2, wire I24 and contact I) of relay GA, and the opening of back contact c of relay S allowing relay T to release to begin the fifth step, while the opening of back contact a of relay S releases relay GA.

When relay S picks up it completes the circuit for the repeating relay MSP, extending from terminal B at front contact 9 of relay M, over wire vI69, contact I) of relay Sth-rough relay MSP to terminal C. Relay MSP therefore picks up on the step corresponding to the last digitwof the code call, remaining energized'until the end of being described, relays is operated on the fourth step, and the fifth to eighth ste psare short steps generated by the operation of relay T over its pulsing circuit. Relay CR picks up on theeighth step over the circuit extending from terminal B at contact d of relay S, WireMB, contact ,1 of relay 8 through relay CR, to terminal C, relay CR comlel, and thence over the front or back contacts 0 of theindicating relays TKS, NW? and RWP to terminal C. Relay ST picks up and establishes a temporary stick circuit extending from terminal B at its front contact a over front contact e of relay S, wireH-3, front contact d of relay to wire H4, and thence as traced above through relay ST and coil 10 to terminal 0;

nections from terminal B at the contacts b of the indicating relays TKS and over contactsa, b and'c, respectively of relay MSP, which are completed successively. over. contacts I of relays I, v2 and 3 on steps nine, ten and eleven of the code, either-oyercontact e of relay LI and contact I) of rela LP, in parallel, front contact 6 of relay CR .and front contact a of relay T' to the right-hand .terminal of relay'T, or over contact e of relay L2 and contactcof relay LP, in parallel, front contact f, of relay CR and back contact 0 of relay, T to the left-hand terminal of relay T, to hold relay" T up or down, as the case maybe,- until relay LP releases. Steps twelve to .fifteen may also be controlled in a similar manner, eachstorage unit being capable of indicatingthe' positions of seven movableldevicesin-the, same code. l V r a When the sixteenth stepis reached, re1ay-R at the transmitting station picks up, energizing relay .116 which opens ;.its back contact 6 to disconnect terminalB from thepulsing circuit for relay T .and'from the stick circuit for relay M. .Relay TVv remains released and relay M releases,

reversingthe connectionsfor relay Rto-render Y relay M releases. Relay OR remains in its-normal position and is not affected by the operation of relay PC, due to the provision of local holding circuits hereinbefore referred to.

The restoration of the line polarity to normal by relay PC causes the line relay R ateach of the other stations to pickup. At thesestations, relays Ll; LP, LB and LBP pick up and then relays L2, LB, LBP and LI release in order. 7 At the transmitting station, even though relay M releases at the exact instant that the line polarity isv restored to normahrelay It may be momentarily deenergized, but since'relay I6 is picked up, its contacts 11 and 2 connect the righthand and left-hand contacts a and -b of relay R together so that the circuits controlled byrelay R remain in the same condition as if relay R remained steadily energized. Consequently the timing relays L at-the transmitting station re- On the eighth step, relay CR establishes conlease in order, slightly. in advance .of those at the other stations. Relay MSP is released by relay M, relay I6 is released by relay LB and relays CR and S are released by relay LBP. When relay M releases, its back contact h connects wire I I3 over back contact h of relay l to wire H4 to maintain the temporary stick circuit for relay ST closed after relay LB releases. When relay S releases, the dropping of its continuity transfer contact e reestablishes the normal stick circuit over which relay ST is held energized until a change occurs in the position of one of the indicating relays to initiate a new code.

A change in position of one of the indicating relays may occur during the transmission of the indication code just described. If this occurs prior to the transmission of any of the indicating steps nine to fifteen, relay ST will be reenergized on the eighth step and but one code will be transmitted. Since the pick-up circuit for relay ST is opened at the beginning of the ninth step,

the temporary stick circuit by which relay ST is held energized will be opened to cause it to release again if a change in the position of any of the indicating relays occurs subsequent to the transmission of the eighth step, Thus a new indication code will be transmitted to indicate the new condition.

It may also occur, due to a fault, that the transmission is interrupted before the sixteenth step is reached to restore the normal stick circuit for relay ST. If an extended pause in the operation of relay R occurs after relay ST has been picked up, relay Ll or L2 will release, releasing relay LB. In this instance relay LB will open its contact 11 before relay M releases, to release relay ST and thereby condition the apparatus to retransmit the code in its entirety when the line becomes available.

Heretofore in connection with starting relays of the normally energized typ as illustrated for example by the relay S of the Letters Patent of the United States No. 2,273,231. issued February 17, 1942, to C. S. Snavely et al., it has been necessary to provide a repeating relay such as the relay SP of this patent, which relay. is restored to normal at the end (if a complete code, in order to make sure that a code interrupted on any of the steps following the one on which the starting relay is picked up, will, be retransmitted. This result is attained in accordance with my invention by the provision of a temporary holding circuit as above described, in addition to the normal holding circuit for the station starting relay ST.

A feature of my invention is the provision of indication storing means as illustrated by the repeating relay TKS for the indicating relay TR, which insures that an indication of the release of relay TR will be transmitted to the oflice, even though the line circuit does not become available for the transmission of the indication until after relay TR has been picked up again. Relay TKS is normally held energized over a stick circuit extending from terminal B at its front contact b over front contact a of relay TR through relay TKS to terminal C1. The release of relay TR therefore releases relay TKS to open its stick circuit and to connect terminal B over back contact b of relay TKS to contact b of relay MSP, to conditionthe unit to transmit an indication code including a long tenth step, indicating that relay TR is released. Relay ST is released by the dropping of contact of relay TKS, and opens its contact'din the pick-up circuit for relay TKS extending to terminal B at back contact h of relay MSP, so that relay TKS remains released until a code including a long tenth step is transmitted. During the transmission of this code, back contact h of relay MSP opens prior to the closing of contactdof relay ST, which occurs on the eighth step, and when back contact In of relay MSP closes again on the sixteenth step, relay TKS becomes reenergized, provided ST is picked up, indicating that the code including the long tenth step has been transmitted and provided also that relay TR is picked up. When relay TKS picks up, the opening of its back contact 0 releases ST again, to initiate a code including a short tenth step for indicating the corresponding condition, but since relay ST is extremely fast, the energizing circuit for relay TKS is opened by relay ST before relay TKS is fully picked up to establish its stick circuit. A condenser CI of relatively large capacity becomes charged over the pickup circuit for relay TKS and provides sufficient energy storage to prolong the energization of relay TKS until its front contact I) closes to establish its stick circuit, under the condition described. V V

I shall next describe how the system is restored to normal in the case of a fault. r

If an indication code is terminated on an odd numbered step, as for example, would be the case if relay T remained picked up due to a fault, the oflice line relay OR remains reversed until relay OLBP releases, and is then restored to normal by the operation of a local circuit as described in my application, Serial No. 496,907. 7

At the transmitting station, relay R remains released, and the timing relays Ll, LP, LB and LBP release. Relay LB releases relay M, which relay releases relay T and removes the line shunt applied by relay T, and also reverses the connections for relay R so that relay R remains released, the apparatus assuming the same condition as at the other stations where relay R and the timing relays stand released with relay L2 icked up.

When relay OR is restored. to normal, the oflice timing relays are reenergized, and relay PC is dee nergized and releases before relay OLBP picks up. The ofiice timing relays then release in the normalorder, as at the end of a complete code. When relay PC 'rele'ases,'it restores the line polarity to normal so all theline relays R pick up in unison, reenergizing their timing relays, and the timing relays at each station then release in the normal order, substantially in unison with those at the oflfice, so that all the coding units are restored to their normal at rest condition at substantially the same time.

If an indication code is terminated on an evennumbered step prior to the sixteenth step, due to the failure of relay T to pick up, relay OR remains normal until the oflice timing relays release, the release of relay OLBP in this instance completing a circuit for operating relay OR to reverse, as described in application, Serial No. 496,907. 7

At. the transmitting station, relay R remains picked up and the timing relays L2, LP and LB release. Relay LB releases relay M and reverses the connections for relay R so that relay R releases, reenergizing the timing relays which then release in the order Ll, LP, LB and LBP, the apparatus assuming the same condition as at the other stations where relay R and the timing relays stand released, with relay R2 picked up.

At the office, relay OR is reversed upon the release of relay OLBP, as above mentioned, to

ace-ace place this relay in a condi tiong correspondingto that df the station line relays B and:v since the pick-up circuit for' relay PC is closed when: its stick 'circuit opens, relay PCremains. picked Theofiice timing relays are reenergized and then release again, dueto the factv that relay OR remains in its. reversed-position, and; relay OR." is

restored to normal upon the release of relay 'OLBP as in the preceding example. Whenrelay OR is restored to normal', the ofiice timing relays are: reenergized' and relay PC deenergizerl,

relay PC releasing before relay 'OLBP picks up.

The-oflicetiming relays'then release the. nor.- mal order, and relay PC restores the line polarity to normal to pick up the'station'line relays, the station timing relays being reenergized and releasing in the-normal orden-as in the preceding examples. I

It willf be seenthat. in each case, regardless of their initial positions, thelinerelays: OR-and R are. all restored to normal at substantially the same. time; so that each releases its timing relay-s in 'the normal order to: restore all of the coding units to their normal at rest condition before any of the relays Ll rel'ease topermit' the: initiation ofth'e next code.

If time to a faulhanindication code is interrupted: before the starting relay is reenergized'. the. apparatus remains in condition? to initiate a new code upon. the release of relay Ll after the unit has assumed its normal at rest condition, while if an indication code is interrupted after the' station: starting relay ST'is reenergized, relay releasing the line relays R to prevent the initiation of a code by any station; When the interference terminates, the system restores itself to normal in the same manner as in the case of'an interruptedindication code, as described above. I shall next describethe means'for preventing interference and for transmitting codes one at a time in the desired order, when two er] more transmitters have codes stored for transmission.

The inclusion of the back contacts I)' of I relays LI and L2 in the pick-up circuit for each relay M, and the provision of a similar circuit for the transmitter relay OT at the office, prevents the initiation of a code except when the line is free, but it may readily happen that the oillce and one or'imore stations initiate codes at substantially thesametime. It has already been pointed'out that each control code transmitted from the office begins with a long step which serves to hold the station line relays'released' for a time sufi'icient'to pick up the delivery control relay CD at each station. At any station at which relay M has been picked up to initiate an indication code, when relay CD picks up, the opening of its back contact e disconnectsterminal B 'from Wire H8, thereby releasing the energized relay Consequently all station coding units are conditioned to receive" the control code onthe first step, the indication codes being stored for transmission subsequently. g

In the event the coding units at two or more locations-initiate indication cndes at'the-same time by theirj'oint action place the oflice coding-unitinthe receiving condition, theshunts appl'ied 'to-the line by thatrelay T which. is nearer the oflice' will govern theoperation of the line relaysR; at more remote locations as well as that at the same location, and the relays T will operate in unison as long as corresponding steps of the respective code calls are of like character.v When one relayT holds ashunt' applied to the line'to generate a long: od'drnumbered step, it willoverrule any relay T which releases at amore remote." location 'for' which. the code call" requires a short step, and? whenrelay T at the. nearer station picks upto: apply ashunt to. the. line, terminating a. short even-numbered step; it will overrule" relay T whichris' held down. at 'a,

more remote station. as. required for a long step. In either-case, the: relays; R1 and Tat the more remote locationswill occupy their released positions simultaneously. on. one of' the'steps of the station code call: fora time. sufficient to energize a'l'ockout circuit extending from terminal. B at the right-hand contact a. of relay R", backfcontact e: or relay F6; front contact b ci relay LBP', back contact. at of .relay T; front contact 7' of relay back contact jof relay CR, back contact c of relay 1 through. the delivery control relay- Clll to terminal Cr. Rela CD will. there.- fore pick up and. by opening its. back contact e will I disconnect terminal B from'w'ire H3 releasing the associated'relay Since the line is now. supplied with current of reverse polarity, the release; of relayM at". the inferior. station renders the. associated relay Rrnon-respons'ive. to; the re.- mainder of thecode, causing the timing relays L and the energized: countingrelay at that station to release, its'code being store'ct for subsequent transmission whenv the. line is again. free;

It will be seen therefore in respect to line action, a lon-godd nmnbered step-takes: precedense over a short one and a short even-numbered: step takes precedence over a long one. For this reason it is desirable to: assign the code callsvto the several locations in: a geographical order so that eachcall is superior to those for more'remote locations and inferior to those for stations nearer the ofiice. In; respect to line action; the order of superiority ofthe-code calls is as shownby the following table, in which each code c'allkis superior to those below it inthe same column and to all those in other columns atthe right. v I

v-isioncf a' stati'on seq.uence relay SS in each station storage-unit; Relay SS serves tap'revent theinit'iatfon ofi a' second indication- "code by It: will be cleanfrom the-foregoing that no 7 any station storage unit which has transmitted a code as long as any other station storage unit has a code stored for transmission. This feature is an improvement upon the arrangements for the same purpose shown in Letters Patent of the United States to Snavely et al., Nos. 2,273,231 and 2,273,383, dated February 17, 1943, for Remote control systems.

Referring to the drawing, it will be seen that relaySS is picked up on the step representing the third digit of the station code call, over front contact h of relay MSP, and relay SS is then held energized over a stick circuit including its own front contact a extending to terminal B at front contact f of relay Ll or L2, whichcircuit is opened by relay LI when the system assumes its normal at rest condition at the end of a code. Relay SS is slow to release and its back contacts b and hold the starting circuit open and also those which govern the transmission of the station code call for an additional intervalfollowing the restoration of the apparatus to its normal at rest condition, during which another'station may initiate a code, and thereby hold relay SS picked up. It follows that when relay SS has been picked up, the station coding unit is rendered incapable of initiating a second code until after the line has been free for a time which is longer than the normal interval between successive codes. Each storage unit having a code stored, at which relay SS has not been actuated, is given access to the line upon the release of relay LI at the end of a code. Consequently each such storage unit will transmit one code during which its relay SS becomes energized. At the end of this series of codes, a longer period will elapse to allow the relays SS to release, whereupon the station units will be again conditioned to transmit codes one at a time in sequence.

It will also be evident that each relay SS serves also to prevent continued initiation of incomplete codes by a station storage unit due to a fault, if other units have codes stored for transmission, provided the faultis not of such nature as to prevent relay SS from becoming energized,

as would be the case, for example, if the code transmitted by a station coding unit having a superior code call does not progress far enough to pick up the station relay S at that station.

To protect against this and other conditions, a thermal relay COR is provided, which relay is energized whenever an indication code is initiated by the storage unit, from the time the starting relay ST releases to store the code for transmission until such code is fully transmitted. Relay SS is picked up by relay MSP on the station selecting step of the code, and until relay SS picks up, relay COR is energized over the circuit extending from terminal B over back contacts b of relays ST and SS, wire I41, the back contact a and the heating element of relay COR to terminal C. When relay MSP picks up it remains energized until the end of the code and provides a connection from terminal B to wire I41 at its front contact 7' for energizing relay COR.

The time of energization of relay COR may exceed the time required to transmit a code from the associated storage unit, even if no fault exists, by the time required to transmit one code from each storage unit having a more superior code call, which interval, in practice, but rarely exceeds one minute. On the other hand, in the event of a fault which prevents the reenergization of relay ST, relay COR is energized substantially continuously. Relay COR is, made selectivelyv responsive to a fault by adjusting it to open its contact a after it has been energized for a time interval of about two minutes, the opening of its contact a deenergizing its heating element and also the pick-up circuit for relay M. Contact a of relay COR is of the snap action type and remains open for about two minutes, and after reclosing, if terminal B remains connected to wire I41, will operate cyclically with closed periods of one minute and open periods of two minutes, approximately. It follows that relay COR operates in such a manner as to prevent the defective transmitter from obtaining access to the line for periods of about two minutes during each three minute interval, as long as the fault persists.

In the foregoing description of the operation of the system it has been assumed that only one storage unit is associated with each coding unit. It is, the usual practice to include one storage unit in the case containing the station coding unit since at least oneis always required, and to provide terminals for connecting to the coding unit one or more auxiliary storage units each comprising a suitable housing containing a group of relays S, MSP, ST and SS, when the number of devices to be controlled or indicated exceeds the capacity of one storage unit. For example, when relay S is connected to wire I24 over contact b of relay GA, so as to respond selectively to the code call 234, the relays S of four auxiliary storage units may be connected over other contacts, similar to contact I) of relay GA to wires I25 to I28 to respond to the code calls 235 to 238, respectively. In this case, a back contact of each of the relays S is included in the stick circuit for relay GA so that relay GA will be released in responseto the last digit of any of the code calls 234 to 238 as required.

Each storage unit also requires a connection from contact 0 of its relay S to a different contact such as the contact h of relay GA, which contact in its released positionestablishes a connection to contact e of relay FA and in its energized position to one of the wires I35I38,to determine the third digit of the corresponding code call. The remaining connections to each auxiliary storage unit are arranged like those of the one shown; that is to say, the remaining wires leading to the station coding unit are "bus wires connected to correspondingly numbered terminals of each of the storage units in turn.

When a group of storage units are connected directly to the station coding unit as above described, relay FA may be controlled on any of the steps two to five, and relay GA on any of the. steps three to six which follow the one to which relay FA is assigned, as indicated on the drawing. It will be. readily apparent that the number of storage units which may be controlled directly by the coding unit in this manner is limited to a group of from one to five using code calls which differ only in respect to the third digit. Other arrangements whereby larger numbers of storage units may be controlled as described in my prior application, Serial No. 496,907.

Although I' have herein shown and described but one form of. my invention, it will be under- 1. In a, remotecontrol system, a group of;movable devices, a linecircuit, a codingunit. for delivering to said linecircuit a code comprisingtwo groups of code'elements the first constituting a f up including said. contacts of the. movable devices and alsov including a contact which opens if the delivery of the second group of code elements is interrupted, and means for transferring the energization of such relay from its temporary stick circuit to its normal stick circuit when the delivery of said second group of code elements is completed.

2. In a remote control system, a coding unit including a transmitter for delivering a multiple step code to a line circuit, a normally energized starting relay, a normal stick circuit for said relay including a series of contacts each of which is adapted to open momentarily at times to release the relay, means for initiating the transmission of a code by said coding unit in response to the release of said starting relay, a pick-up circuit for said relay closed momentarily upon the delivery of an intermediate step of said code to the line circuit by the coding unit, a temporary stick circuit for maintaining said relay picked up including said series of contacts and an additional contact which remains closed only when the coding unit is delivering a code to the line circuit, and means for transferring the energization of such relay from its temporary stick circuit to v its normal stick circuit on the last step of said code.

3. In a remote control system, a coding unit including a transmitter for delivering a multiple step code to a line circuit, a starting relay of the biased polar type, a normally closed stick circuit for said relay including its own front contact and also including a movable contact adapted to open the circuit'momentarily at times, means comprising an inductance coil connected in parallel with the winding of the relay to provide a source of current-for driving the relay to the released position in response to the momentary opening of its stick circuit by said movable contact, means for initiating the transmission of a code by said coding unit in response to the release of said relay, and means controlled by said coding unit when delivering a code to said lin'e circuit for reenergizing said relay to establish said normally closed stick circuit.

4. In a remote control system, a coding unit including a transmitter for delivering different multiple step codes to a line circuit, each such code including a group of elements comprising a distinctive code call and another group of elements for indicating the positions of movable devices, a plurality of terminals on said coding unit for connecting different storage units thereto to control said coding unit, each storage unit including a selector relay and a starting relay, a normal stick circuit for each starting relay for holding such relay energized irrespective of the condition of the associated coding unit, said nor-- mal' stick circuitincluding a back contact of the associated selector relay contacts controlled .by one or more; movable ;devices which are adapted to operr the circuit momentarily at -times .in response to changesv in the positions oi, said devices, means including circuits closed. in response; to the release of such starting. relay for initiating thev transmission of a; code by said coding unit, said codeincluding a distinctive code call identifying the particular starting. relay which is, in its, released position, and also including an element. identifying;v the position of the .movable device which released: said starting relay,

- means for energizing the associated selector relay in responseto such code call, means for closing a, pick-upcjrcui-t to energize such starting relay momentarily; when the associated selecton relay becomes energized; tothereby establish. a tem;- porary stick circuit for such starting relay including its own front contact and said movable device contact and also including a timing relay.

contact in said coding unit, means for maintaining said timing contact closed only as long as the coding unit remains in operation to complete the transmission of said code, and means for releasing said energized selector relay at the end of said code to reestablish the normal stick circuit for such starting relay before said timing contact opens.

5. In a remote control system, a coding unit including a master relay, a transmitter in said coding unit for delivering a multiple step code to a line circuit when said master relay is energized, a normally energized starting relay for controlling said coding unit, a timing relay in' front contact of the timing relay and a contact which opens to release the master relay prior to the release of said timing relay at the end of a complete code, a pick-up circuit for said starting relay closed momentarily on an intermediate step of the code, and a stick circuit for maintaining said starting relay energized including its own front contact, a normally closed movable contact included in the stick circuit for said starting relay I and adapted to open the circuit momentarily at times to release the starting relay, and means in said starting relay stick circuit comprising a front contact of the timing relay and a back contact of the master relay in parallel for releasing the starting relay in the event of an interruption in the transmission of a code occurring after said starting relay has been picked up on said intermediate step.

6. In a communication system of the code type, a normally energized starting relay for initiating the operation of said system, an indicating relay, a repeating relay for controlling said system to indicate the condition of said indicating relay, a pick-up circuit for the repeating relay including front contacts of the starting relay and of the indicating relay, a stick circuit for the repeating relay including its own front contact and a front contact of said indicating relay, a normally closed stick circuit for the starting relay including its own front contact and a back con-'- tact of the repeating relay, the opening of said back contact being effective to release the startmg relay in response to the energization oftlie repeating relay prior to the closing of the front contact of said repeating relay, and means comprising a condenser which is charged over the pick-up circuit for the repeating relay and discharges through its winding for maintaining such relay energized from the time its back contact opens until its front contact closes.

7. In a remote control system, code apparatus for delivering a multiple step code to a line circuit, comprising a transmitter relay, a pulsing circuit for intermittently energizing the relay, said circuit including the relay winding and two resistors in series therewith to regulate the pickup time of the relay, and means including a front contact of the relay for short circuiting 'one of said resistors when the relay is picked up to regulate the release time of the relay.

8. In a remote control system, code apparatus for delivering a multiple step code to a line circuit, comprising a transmitter relay, a pulsing circuit for intermittently energizing the relay, said circuit including the relay winding and two resistors in series therewith to regulate the pickup time of the relay, means including a front contact of the relay for short circuiting one of said resistors when the relay is picked up to regulate the release time of the relay, a stick circuit for holding the relay picked up at times after its pulsing circuit opens including its front contacts and winding and the other of said two resistors, and connections including a back contact of the relay for short circuiting its winding at times to prevent the relay from picking up in response to the closing of said pulsing circuit.

' ARTHUR P. JACKEL. 

